An ACX7100-32 acting as a transit box in the path between a DHCP Relay and Server is seeing relayed DHCP packets dropped after an upgrade.
The topology is as follows:
DHCP client ---- MX DHCP Relay ---- ACX7100 (Transit IPv4) ---- MX DHCP Server
After the upgrade, the DHCP packets that have passed the relay server which are moved to Unicast are dropped on Ingress at the ACX. Statistics for DHCP Relay show the same:
labroot@h09-46> show dhcp relay statistics
Packets dropped:
Total 425
dhcp-service total 425
Messages received:
BOOTREQUEST 0
DHCPDECLINE 0
DHCPDISCOVER 0
DHCPINFORM 0
DHCPRELEASE 0
DHCPREQUEST 0
DHCPLEASEACTIVE 0
DHCPLEASEUNASSIGNED 0
DHCPLEASEUNKNOWN 0
DHCPLEASEQUERYDONE 0
DHCPACTIVELEASEQUERY 0
Messages sent:
BOOTREPLY 0
DHCPOFFER 0
DHCPACK 0
DHCPNAK 0
DHCPFORCERENEW 0
DHCPLEASEQUERY 0
DHCPBULKLEASEQUERY 0
DHCPLEASEUNASSINGED 0
Total 428
dhcp-service total 428
With DHCP logging reporting:
labroot@h09-46> show log dhcp.log | match drop
Apr 21 11:17:39.947937000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:40.968248000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:41.948934000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:42.970558000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:43.888432000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:44.908746000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:45.888313000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:46.969058000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:47.991520000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:49.69189000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:50.89902000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:51.49080000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:52.69586000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:53.52187000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:53.950070000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:54.930629000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:55.990082000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:56.976787000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Apr 21 11:17:57.850780000 [MSTR][NOTE] [default:default][RLY][INET][et-0/0/0.101] jdhcpd_packet_handle: dropping packet as routing context is not configured
Filter hit in the PFE tied to __dhcp4_v0_L3_67_u0__
labroot@h09-46:pfe> show evo-pfemand filter counters filter-name __dhcp4_v0_L3_67_u0__
Counter-Name Packets Bytes
dhcp4_v0_L3_67_u0-rule 509 153209
dhcp4_v0_L3_67_u0-rule 511 153811
labroot@h09-46:pfe> show evo-pfemand filter counters filter-name __dhcp4_v0_L3_68_u0__
dhcp4_v0_L3_68_u0-rule 0 0
Note that the ACX has a VRF set with DHCP Local Server configuration:
set routing-instances INTERNET system services dhcp-local-server group g1 interface lo0.100
If the DHCP Local Server is removed, the problem is not seen.
For the packets to get relayed, no-snoop needs to be set. It can be set in the DHCP Local Server RI:
set routing-instances internet system services dhcp-local-server no-snoop
Or, dhcp-relay with no-snoop can be configured where the interfaces that are used to forward the Unicast packet is sent. However, all potential interfaces that could be used need to be defined, i.e.
set forwarding-options dhcp-relay group g1 interface et-0/0/0:0.0
set forwarding-options dhcp-relay group g1 interface et-0/0/0:1.0
set forwarding-options dhcp-relay no-snoop